There has been a high-power luminaire used as a floodlight, a spotlight, or the like for lighting a signboard or the like or illuminating a building. As such a luminaire, in recent years, there has been known a luminaire including an LED (a light-emitting diode), which functions as a solid-state light-emitting element, as a luminous element for the purpose of an extension of life, energy saving, a reduction in weight, a reduction in size, or the like.